SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd1813f50a5a281ab3e4d6e002a93374680357617d9655fd42ff5edc905f6e11d' 
  AND token = 'd/i+sze3I+LvHN4y0XwbkohY64n9jBcH2mseUQsxcsE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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