SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '681355a634c1c17f0251ecaa4e1fea85a34e736ff654540f03c5e3ab08dea2d3' 
  AND token = 'A+76nnmQesiPkSqmd5HPQsGt7XGSEB7Ysdw4wG8hX4Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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