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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a392ca495a2a847a75e23075b6ec5b61c76c38c23a5001a9dd9a7d3c262d5846' 
  AND token = 'Jc/3Nm1LVGlXGZAry0ANRjKaFZ4qgYytk9DJQWcuEJE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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