SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e7c0f966118b2b5e7a73132d07584edeee15800ca021c98811525f109b68515' 
  AND token = 'WRyIFRyKuWtQO+rT9cfwftuf8/A877Y+QXhtRVu5aFk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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