SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'be282a7901c30b61d87229cc47f5981b36b598686f7f0a939a43dbe81214784a' 
  AND token = 'DsWdgtnxIitOc7xpGNhKzbCBUuhXgutuEwaRM/SIJAg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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