SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b4e97392af78c925c1fbdf49e9aa6994621f75c4d2d7c08e23305f8604af5bc' 
  AND token = '2SD+WF3e9iE3ALljHHNgTuPqTNVj6pMzhvoAsunvrnk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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