SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90c6cbfbc0b0c2bebd949fa315b6e4b8462f30e3be8f9d9bc6688545767cc1c5' 
  AND token = 'OehRLPzhvdnfUZGjqhZHklBlxJGjOJXM25cAKbDKPKk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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