SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b16cbc19f439c45f6de343a60541d664bdc8d6e3142ed799557de4feea9a7b5a' 
  AND token = 'sWfaZSCNnWjC5piCHYGi00UR0DlHJwJDGMT8/OKmvM4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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