SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a58fe14a935775db46bbf68eb462ec5809ea2c2f5d2d14a8b66ea9e56d2ebf74' 
  AND token = '/vhVcitSQYPgqoppDv8LrL5bsUoXDL+foMMqFj/sI/Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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