SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '758f263136f92e76987fea22a402916a0cee41c77acd76163fe9b6a85b83eda3' 
  AND token = 'LziXlfFgmlzlRxSbD5abADcrUfAA5rFsja8fPGb/rhk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}