SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0550c2b2b8209742e87073995c2a57dea58236e93dcbc1fb5604becce5f502ab' 
  AND token = 'ys0fQLbhltrKxQ3H/1rziceE+TJ10h8chVpIYfcZlpE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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