SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0b46e79021813b320074e7ca8f97c4931165c334dfe74cb139a86df50ee0f5f8' 
  AND token = 'nJi6iuQb58CeQvIqtqgbE6URNRFdb+qiixSkVNskes0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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