SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '03adc9f75db2fd08b1aec519795a3b208433c6bb24baac4c955477861f9bbced' 
  AND token = 'zA5sLJ40yl0fkkCJg+xjiF9mcXGZoxSsVhu8xl+x41E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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