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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c14c9348ea322c7b1f4f93c02a366d7c5a27f1b4332fc0e85409bdc54ec063c4' 
  AND token = 'UFg9plqUpw9SJbL1WBQFX/4Ts1EbnEXD+iztRAVH2Aw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00010

JSON explain

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