SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '419e44263a3170206921ac790d5b3ccf7230678518094fa90d2858f31340f174' 
  AND token = 'ul4GVkTcLaJ+ZCydwvtltVLLUorEwFIy7q9v1jA8cUE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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