SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '69131914544544eb4224e3ca7f89d9315967300db3f554f721f717a5e7529c2a' 
  AND token = 'a3x/6RfBYE9wtQCjHK8sFESLwoWuTA7JXcp+xhumFQI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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