SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31f05cc9900e472749957b9c9f7392eeaa67b7b48e0457e38d5219801598efee' 
  AND token = 'zwPCWbtnvgAmz9oezXlCxQlt7GVGr/dBaL7HAORyELY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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