SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '369159adbc532710c7e2ae45743f92417c7a869b0c9e4825e9e723434519997f' 
  AND token = 'A8G/XbxFZQ79JZ3ttg2QdGJmbVxpY7Kj+sIprGqO9mE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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