SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '8bb15f9febd340ea1c0a933480c7c8ef838bfcb55b6ea14cd5d2051ac3b50d03' 
  AND token = 'VtgnVF7lV2WVrkoNxkOz6TITQ/MUP7Uri0cZtwZqevY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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