SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd663b0f8912c66f0b992c331bacbf523e856fe2858df56a92e8370b631114651' 
  AND token = '1r8HxeDK80gIXyk1KEOflHwGnt5ff4zXkGfVdUTkg5U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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