SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d2bac5238cc611565f42d6b240785c017c043a8ea93baf099ed77a3459d5021' 
  AND token = 'SQJhhL7QIX6xYjj5AkHvLlifDbcygR+EGsZE7hbrYew=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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