SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b860ceb06a194f82c5356b9baa3eead788db86cb4586825e1eb97c1943cf8db6' 
  AND token = 'KbiqkFs1SCQoYs0jGAG4IeJZRLT5xC0POhl2swYxviA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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