SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b36535328cfa2db218f3d5453d61f8367b7e09921fd4b9de4b2c681dbd85571a' 
  AND token = 'NkewvuiCmxjW1WQ0rCusBwqEdh7DZxoHcVsVsfwLBFw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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