SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8246eeec3c33890918ce46a1e75de8b7d40a634e0397645057ad26f1e6239fb' 
  AND token = 'xpnvXeH6EWYkQEI1eXyEs3efPhrMIyb3L0XQQ5T5f+k=' 
  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"
    }
  }
}