SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99155bc4b6f155dc312f9013ba93f38e1ef3fc3840b25765a4b3bc8bba1b5d62' 
  AND token = 'xh/k0P+d8ncLndwDc0Z2wSipsenBLVogmfribO8JUg0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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