SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '62d2a77330b886fde64e1fc0c3e11445b5568434a7f4097bf96352866b2a3db7' 
  AND token = 'd6fVcBQzlHv5uBnge8+auGPhn6swvdDk14jY64d5jDE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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