SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f498d104debd22bca89854721d55c659e274ddd43aea518cdcd605aef63ac916' 
  AND token = 'gKsf+jF4b4z/ZfQjPoXDgvFFTiEIKd6RvD5aZJmVpLA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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