SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7a2d887f8f65301f961c90bae0d546b3e30e468ed52134a266df7187d47dd101' 
  AND token = 'D5HhpdL45H4cpnsTDU8j7xh7uiycDsDK1n+ABeGwUAE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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