SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31ae586235a5aceeb92739f0949f7284afa891d4d68a04ea2bafaffa64088adb' 
  AND token = 'noN0I3Gse1KoHY/3sxRl1hD4phtgIb5fAO03LfjEj2I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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