SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '375f514bd64e52bb3877ebe8a92841fe8b2c693a6d601432d52f803547ebb607' 
  AND token = 'SdrqYbgp8dwCilngzsl58GmGuuJmGhta959DYIipUAs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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