SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4889639345743fdf9bb4be39bcbb6f03f1120bc485e14e23a4f4b3944d21489' 
  AND token = 'EepyFGQ9Lpd34AteZX9F1bfhKtlbfer6Upm6qjkFCxs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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