SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c290aad559ac6c511b0423505b4fbe9d541d8eef7554e669353b3c4c6d803cc6' 
  AND token = 'wBWkeX4708HZ/gkJqMEixJyZxUCCKPezFBP+p+5DDCE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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