SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ac9c0b7518b65b3fde063604c08c516aa880e2591f0cc62badc5cf993f060704' 
  AND token = '5OVpdnDzC+lDScnWgLz9/T+uPPgmMUnPYq+bxwPdg24=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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