SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '574a7f9791abfa7c2d95c321535321cae852c0db04b0b39512bfad3c86b7368f' 
  AND token = 'vn5YaFw4gFNZUPeeTaQjPbVsZ4bVDrvoS/SZMwlzOfQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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