SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'beba0a21f362af1429fbb81d1bf71cd53c29476184887856a269e51d7fd202a2' 
  AND token = 'K4ERO6LoEWWJgZceV+Uju4QJCAA/8lGq6zYvM3cICa4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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