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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e389fcedc5af1bab4d690aeb4894c21f9dbe315ccf2a49c30458b681f9dbfb8' 
  AND token = 'ESDhFG4QV6+sVjqYCFDT9kDLNbwmKnNsNzn9Q4YDog4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}