SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6d82d8f071418de40c7b491d4546149f81c4bcf289b516ebf3141ef278b130b4' 
  AND token = 'wqdETJurFZUc4c+H5Sb8WQc1hogicdviQjbGXQcIbNA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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