SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3be7d227e7df60fc57980b0a5dd21a421d5464b079b645b189a9bea5f762d6b' 
  AND token = 'LNmOlB3DLcFfpaQEMTHPfH1mfcXPZvoN/A3Pn0kNwcs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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