SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40b81242f83c1d4fbca8c57ca630c13ad665440581b931d52c9dda9df7e7c684' 
  AND token = '4vCRVhpVYIBVYC2Xg/FNlM+jtd6k9AZusret4nJeXnY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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