SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ac1d056d30251c5295e02616365a0432f40d7cc5beca533c471339704bf5966' 
  AND token = 'KmZYIhM6ulPUUJx3xkbtuTMlXzEjSU37Di7FdYnTJwQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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