SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '1d8d68f23495631309be04ec7ff9d41174f9c7cc49a0e9bd1a1b53ac2545e0b6' 
  AND token = 'NRLm0oyV6vW0PdDZFh32KPz2rdgwzW4SBRfa5LoYuJE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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