SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8355479bd8e551368b4fb97e7e4d068f13cb31669df636bd584bc30afd76744c' 
  AND token = 'MOgc3v2vL+tqoBRiTgXK0CHpUcoNm+2oBxwRs35VHU8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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