SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '72b9d5124f793ae632e6fd37bbb267131f651f238cd790a17b26647042d1fde4' 
  AND token = 'l42uDp7ECPTFbjPvMusbFCyo66YlBFNNV8XuB+UsJ8E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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