SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '766a79ee64d0606479815d0d6c441bf93f7cfedda42573be1a3e862465b6f5cb' 
  AND token = 'T9gspnc9CtJPSq+VEV5vaQ8MHYQeQYPUYETFvugaha8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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