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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d83ffa5a35e892d032c706e2f4655dd380c951684ea305e4310ba44615e72c0' 
  AND token = 'Nr5ZMyr1qZKq+7YGO0WUUQQybe4DFSvqTSIRplfD57M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00009

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}