SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '375dd9756d799a7a840a1c029991a2212c43562c44254bd32fcfde4823fafb75' 
  AND token = 'mxBhL5NpVRj8sch+xLIGTJ4U+NtWpupuw8+EmomzK74=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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