SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '0844e215001e83c08983d9e788047b03cae10ef09fce368d2eda4a82677a0368' 
  AND token = 'OORz6m90s0pN18b1tsvUch9Q8GOG7GJQnKLoUY/3TYY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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