SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e15a4d954ee7977bf7ff58ba805b53a5c4ffb8484b333b8ae07648a13e9068e6' 
  AND token = 'heEKZcVcMHgElHz6BlEFYvINdXeo3KxWNEtjoGV6aRI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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