SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '30b2dd6a8163429831cd5b88249359184d083c2c08682e1769021344122797d6' 
  AND token = 'SfrbDk98kdf2ZCLec1RIxaelIud3EV0oWr+Fx0/pdkU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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