SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e156b04900e49a4417808c5da12f991da009490dec088b4426e800d6cc77c30e' 
  AND token = 'csFYUwGi6n0rrNkGipb4dxqTmpqECE+6qdwWGqvueLw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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