SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15c8ebbddda494c70842b97159c4a56ff468ce987a907fd36ce28614425c77b9' 
  AND token = 'NHk1vdDGjIP25T/3mqC1G/lLsh5UXQadCKa+NjaNR3E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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