SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '728d4e952e12e15aa805950248e9153a328757ea4ed3952be97bc887f6b46437' 
  AND token = 'tICRsZFWPBgoEdzO+ijufGyJOkZiQbETJ8QZLmjZI4o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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