SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c2baf4ce125ce818ae5082a7fba66df6959efe3bd69487985a215cb432f5c44' 
  AND token = '0RR6OSfhh8OIqRdmGQfrBkjGNCEynTNIHhcR+kkn/UA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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