SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '0771bb403657720057f036699eea23edf47f4096163ef4e60784a0013477376f' 
  AND token = 'W9uPD4gFcE/bjlBtUUR5Gwxvgz3nNVHzyJqSBA4GvnA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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