SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6b77755addf0b87fcc4519fa025152e424d293083a8688fb6ff91e71e18dd921' 
  AND token = 'TGkD3GUROC33IKM7dB8PUgYEl3/2YHrz7rdvixwRNto=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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