SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a65d2efef1fcf0face2af296b0bb3684968fbca0a3ccee5338a64a84f6f226e5' 
  AND token = '/KEQp14ArJ3pjlQDWR8AjorE3XYLkMcRtUFsqC8mBEk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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