SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3504eb95b3cfb1409e1ca73acefe5d7b20ceb083457210925038dd959577f2e3' 
  AND token = 'ucySTSR+m3IgvoFhUtvxx/iSPtEn6t96MA2Ye/WEN4M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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