SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55fdc54a7413b408d973ebc6772e40402aef0bd7a8fde07110ffb84391393f0e' 
  AND token = 'vvSKWLkvCto0iKAGoJUIGDHHkzoa8Wrb5mn6utA990E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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