SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1cbff5883982553b345be78d627d14db8549a7caba812b59888d2a4e8a3c29e' 
  AND token = 'myPwbcHqQI5Luuw1vh1Znhz10D+wz9zoXnUgssYzC2g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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