SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '523521acea5e246424464c92cd8481ab103757ad047505f77169970342bdce8f' 
  AND token = '0+NrmnQVG0u0G8QrmzVaBxmBqis8nFrX/H4cCC47BGc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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