SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ceae7c791b8c6567d0cb4d242136be0479ccc20f4565b21a557278d83ba00b21' 
  AND token = 'A9zL0NkEusESBojEJYJ/U0sUuBRAC0HwvVgZWp4lC+k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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