SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb6e6e160037ebf54cbb6b552891655910e41f7064eba0324b50e8596ae9aaee' 
  AND token = 'dsRo7XN3AFVoP9IHpjkIA5jm2+ysloNl0euimZBnTNU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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