SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75b377a9511fb73e0ce2116560508afade788e4b8427ba06bf24e099b954befd' 
  AND token = 'K7UpZKK+Cug7iWxUf1JXVGvzDWIOgXjkf+pqLOScbqs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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