SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b455cab48d3f646d1ae3c87c4c369835dad4d11530c776adfac5895049c04657' 
  AND token = 'HJjXrGgdnLpOzsr6Cohq5fPilRaOZ0sE/EuMVxFuXFg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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