SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52a7ae6252740477e5b31e7c62f75ade22eb45050e90224569d31c7337631883' 
  AND token = 'DCcjCFwwNWBgARA+wFOiVqzp1JDK41IJz0RBmCV+IL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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