SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8113ee3cd32b51ad19e29c3949353635a79f92b555537b953362771ae1082a79' 
  AND token = 'txkjg3mfUzAJ1NDTD+M1Jtr20kqMHilmp+MacYYoLv0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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