SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5546be91cedfe311a3195abc27935af22f3321ef84ef121c31e35609e626d9ad' 
  AND token = 'Bk1p6HdrCAO5TgAKMbsxlll2OjjpLiRhWHphuto+7jA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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