SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2b1ef8fc78dda6b5b8f22801b86c6007f9999fdc1526f9a9a58fce4ba235866' 
  AND token = '7VH2+vB8l4UwjI3SMfrZu6MFvA8ZhJ+jw2+GqXQ4XiE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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