SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff91364f76ac4606ccdef900c4cd045df90686b8946d8f53a6fab0b38dc65d54' 
  AND token = 'rStvKkAJDROngkhfMzz2+WCmpOm2nHgmuq2FyzN36Os=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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