SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0a4d67824dc558924e9132040ca6441e37f009900526254b8a42ddb49bef651' 
  AND token = 'L2n3OALTYkfWGtTG9fSu68ZU6hOV0vmgzxLUOVkusb8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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