SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '582bf93c45b8d627a277ec45b042649bdbb2b671bd39add98d81431efa4f1901' 
  AND token = '5eJ/gQxM6HLeSBnh9waFjMjljwlTxXLN7ooGFoQ0UMM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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