SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a9584618d89db2a5bdd112821a5f7f0f8297a58fd672d98b0c872717d34da03' 
  AND token = 'L7l6yaA8pd80tbT3TqMKZfWasOEbIoh3WqvQ7veYSAY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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