SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7a8d1f612d0428182ad07195a4bef0a509898773a92c282c73332cfb9817f5c' 
  AND token = 'O3CtePxlP6OKJ8eaLQJ6zmCtYafGnE9aflGdT5u9ZqE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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