SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c63813db8b55756446f7f99e514de09f3c83b32f5b6870d2947366a8d6885064' 
  AND token = 'rVOppLHoAQgaEobJtt7KSHNqx5N/8Pi4j39XHMgwxBc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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