SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3781e873933f893cbd6a8955fbf8534d91cec21c8f9a8b2d705dde22728ed11' 
  AND token = '5M4HLQMhaagVScu0VAkpxsK+ISvdhb+ohBcfzkmuJUU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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