SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7a8d60b42619e646326764de979c8aa4cc92d4c32fe1cd5208ee300128a3e31' 
  AND token = 'u+PwnlMU6EZeC+osmWmEYq6lklEYDOM0IhVVfjJ/K9Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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