SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0a78a7cec445d4bca708aa098f449c7fc688b901f9a478cd3be907e14955cc32' 
  AND token = '1fkYNOHnliaRy1SQwuPPlHM5yPVdVLLaTZUgv/C/W88=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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