SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3df42f7ac024789767e6e2cc5456bfcae81d40f92787f690f7baf11080bb3002' 
  AND token = 'xXiuEEI1kGusVmOVZtoJN2W1PjN7O1e+YShOcoUM7e8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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