SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42d3266b19baed7ecd1dde4f3dbef461b85d8b79c4b86fd4d4f452ff564dde12' 
  AND token = 'LGq+VxaXhQT/N/Pwtu5tMVFYWXhNZkUF2Hlrja3l3bo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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