SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6f9309f651f372d1430e692db7baadd29d10a36405607f07dff930a7691dd86' 
  AND token = 'IFi3iHSVkiqwUOj2X89dyC+hT3yE7A6PQlbkbbdNsbM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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