SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a8c7ddc81d8b51095d2ac746cd3eacbb9365b21fe7baa531d924a5d8efb7d25' 
  AND token = '24tpvmKPsmxpVQGyyJiXrjt0gjWLmq0sSPf5+CX4cBA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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