SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a39e07693185b3ac62256df62409509efe131661fc8a630577328fc48c8ec679' 
  AND token = '8L/Yw2CtoZmIQTd2PRqFZBbN/FhkmDdVl5PM5vohVGQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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