SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3f41c96382cd48459777e21c8cb4d05c59de5209811d3a36d3acbe6bfd810feb' 
  AND token = 'YQadz/pqjKXUHzL+n+3hPP50H+1avtKDGcaEalAPFqg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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