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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3399b09743cf1c0064d8e7c0af80f2e77a06b9449ec25364226d1ec1482cce0' 
  AND token = 'FI+TXnqz7AjzQXFWi8mjA+yx5JmwaFdDVR0cbR8u5Tk=' 
  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"
    }
  }
}