SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '877f6300cc226b1ca5fbb8b1d5a4fffb3cf71ecba7e853985588fe98e38c5bbc' 
  AND token = 'cqCdoMT2ps9iDZdicVFOHZJUqVtTsEzPoGiXYHt4Rhk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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