SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6659ab07eb4165e0673c5bbf45e08e186a8c48a3eb4d5869696575084ae2d670' 
  AND token = 'e8D9MlCvcExlwrOw16XkRFMsLu/rClT3wpO612WPs44=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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