SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '984ba6d4b9aa6001680209812734c5e5df7892d42ce2a39f95e4510862135a6d' 
  AND token = 'jqV1BL/CunUYr5JV/kNY0EIVt8+bz4yCLiOvEKqKirg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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