SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd1c56c515bfe79828073265989683fe706440b6f4844f16d3c7451b786f5c27' 
  AND token = '/DqTFCxPiKhjO7Bui+VHwsO2xxqYzcQqh0kBTD9PXb8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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