SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f09027741ac91bccee0a83ef02c769855c91beade0d958877af82c01c6a1b10' 
  AND token = 'uN0L9bSGVU1n8ZbJqLZw6FNfnaQIqNhjCHkDUNFQBpU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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