SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b64df01c618ce6150398a76f2bb5a849a367315813d1b326a7fb14488ee82386' 
  AND token = 'Liz0ws2i3xA9e30gm7wVtsQovTsuia15YseUlj32J3w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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