SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ac3100ed8c5657faec2bf75b72239517f89eccd5aa5038736186b4c6c0d1246' 
  AND token = '5jgDp5GZN887DLNJBNkJaysWWsNQSCiownw9msgJZ3o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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