SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16c3db9b7f644d05c6b90af9a3037f98d0a68fa43547da320eff63921df1dfe7' 
  AND token = 'fYg4Y5D+79WfwOS22CkdCSByWiql8DV04MtLKr3jAa4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}