SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3fbe91d8d34b022e7eba745804a41d6c22707469d07ec8ca421750d78d9a0444' 
  AND token = 'nk9xW5T8vujGh6XJtYwS7IncLJ109G6WhWc5pc4Jkio=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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