SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f4f8ec70fa84167be961453d5c714153906351b622d8e5db546c94fd09de89d' 
  AND token = 'TRlReZHkWgYZNn60O2HWC7wmFrxSqn69dwkTDt2CNpM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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