SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28615f11a64d3796b558c00a2081c115856418a54f87ac9b8021150c854c8574' 
  AND token = 'sQCzgtDlpckHDo8FarmtGlIm7NKKl55N04wODMeMnG4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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