SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6d3969a455097579addafa233c0714c9ec67aa44bd7ebd1cc6b9fc44c1bc4ad' 
  AND token = 'guOPiGOSD/mHfhhh0IKrLwE58P5K2xWV4NEcTcCfpiM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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