SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ce1e2607007edf879a3dd88ed8da095452861a3e92c713a3a1a411fbd403b98b' 
  AND token = 'fG07fAiXzOkvzlU+fZofJiWWdb6lXSvXTSlsjPAbICw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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