SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '615f5df991093a93a888728f78f0c3aaeb8d40827da68aa8c1108cc7b5efa81f' 
  AND token = 'P2gq4oNuhyERhHZWSTpJeuJr4fxIz9wt2jllHzejfhA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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