SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2636c0892f680992be6cf92b9d4b3bab43e34e09556b067ceb15982bce5b94a7' 
  AND token = '0pTr5XtkT0zo/J3IHxKOceN5SHh6x4CTy+nSkm9kT/o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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