SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b2e745b87ccc5864431473423a9020e3cb57ffc1bfe1dd5d12ae4257edc08f3d' 
  AND token = 'yYhW+9isDx4zHkvZ6l1Jq/YY/RhvLKJe1fSCdiniUpo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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