SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87015e99fa69af1dfa78d560440dfa37d9bdb550ef8044343642d97c1ff65e98' 
  AND token = '4qcz0qF0oJHiq7tKq5RyiHNtNkVyEcKu+xHrRAa1GWE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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