SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e5bb0edcc0638f6863893283a3401c1f5179e7dc35fd45e2060b0fde098e40bf' 
  AND token = 'bVa7wV8vlP6Tp0HLAK/wBZPncxiIyP1Dl4TFsdHv0Ps=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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