SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4bd722d3362f5fd92f516ab4e328a420ecb62297bf2b6255c23e5fac9cda261d' 
  AND token = 'FBQLh4N3ycAd4iijC0LC7nLvG193BoHovvkC0rCZe5o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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