SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dbf15a2a092fb668eacf31483423238ed2b6f6da0388e93e1c04164718b09449' 
  AND token = 'zTRzmVxrBb+xvY7l8YA8MOtWQc/iZvLKsHJXb5VU3eM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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